1. Field of the Invention
This invention relates to microwave and millimeter wave integrated circuits and more particularly to a planar power divider/combiner circuit which may be used to divide an RF signal into a plurality of signals or combine a plurality of RF signal sources into a single signal.
As used throughout this specification and the claims, the term RF signal includes both microwave and millimeter wave signals.
2. Description of the Related Art
Power divider circuits have been developed to divide RF signals into a number of signals to feed multi-element antennas. Conversely, power combiner circuits were developed to combine the output of a number of solid state amplifiers, chip transistors or oscillators. Several different circuit geometries have evolved to accomplish this power dividing or combining such as: The circular-geometry Wilkinson power divider disclosed in G. J. Wilkinson, "An-N Way Hybrid Power Divider," IRE Trans. on Microwave Theory and Tech., MTT-8 No. 1, pp. 116-19 (January 1960); the fork power divider disclosed in an article by A. Saleh entitled "Planar, Electrically Symmetric N-Way Hybrid Power Dividers/Combiners," IEEE Trans. Microwave Theory Tech., MTT-28, No. 6, pp. 555-63 (June 1980); and the radial power divider disclosed in an article authored by J. Schellenberg & M. Cohn, "A Wideband Radial Power Combiner for FET Amplifiers," 1978 IEEE ISSCC Digest 164-165, 273 (February 1978). None of these power divider/combiner circuits, however, can provide phase matching, ultra-wide bandwidth, impedance transforming, port to port isolation in a planar compact power dividing and combining circuit all at the same time.